At the close of this Tuesday’s episode, CBS’ Person of Interest will air a promo for a “three-episode event” that promises to make the rest of November sweeps unmissable, perhaps a bit devastating — and TVLine has a first look at the intense teaser.

First, I must warn you: The 30-second promo, set to Sun Kil Moon’s haunting “Heron Blue,” strongly suggests a major plot twist to unfold over the next three weeks. So before you lunge for that PLAY button, ready yourself.

After you have previewed the promo, consider this statement issued to TVLine by POI executive producers Jonah Nolan and Greg Plageman: “We promised our actors and our audience that these characters wouldn’t be static, stuck in an endless loop — that they would have a journey. And, of course, every journey comes to an end.” Yikes.

Check out the chilling new promo and share your reaction to its gut-punching promise.